This invention relates generally to the field of photography and, more particularly, to an improved separable two-piece photographic film spool as well as an improved method of manually loading unexposed film into a film cassette.
Multipurpose film cassettes have been developed in which a strip of photographic film is operated to be exposed, processed and projected without having to leave the cassette. Film cassettes of this type are disclosed in several U.S. Patents assigned in common with the present invention.
In cassettes of the noted category, a supply of unexposed light sensitive film is utilized. For selectively exposing the film strip, the cassette is inserted into a camera particularly adapted to receive and operate the same. Processing or developing the exposed film is achieved by removing the cassette from the camera and placing it into a player or processing and viewing apparatus. Such apparatus activates a cassette contained processor for depositing a desired layer of processing fluid for developing the latent images on the film's exposed emulsion surface. Thus, the conventional series of successive, positive transparent images on the exposed film are developed. Following processing in this manner, the player is operated as a projector. Accordingly, the film is advanced incrementally, frame-by-frame, past a light source so that the scenes to which the film were exposed can be projected onto a screen.
The current state of the art with respect to this type of multipurpose film cassette is represented by the disclosure of U.S. Pat. No. 3,951,530, issued Apr. 20, 1976, to Frank M. Czumak, Paul B. Mason, and Joseph A. Stella; which is assigned commonly with the present invention. In the disclosure of this patent, there is described a pair of photographic film spools rotatably mounted in the cassette housing. One spool is for take-up purposes, while the other is for supply purposes. Each of the spools is, however, provided with a pair of opposed and spaced apart flanges affixed to opposite ends of a central hub. Opposite ends of the film strip are attached to corresponding ones of the spool hubs so as to allow for synchronous winding and unwinding of the film. Means are provided in the player for selectively rotating both spools for achieving the desired winding. The spools are of a one-piece molded plastic construction. While the spools function satisfactorily, there remains, however, potential for problems. One drawback is that since the space between the opposed flanges widens from the hub to their periphery, due to the required draft needed for molding purposes, there is a tendency for the outer most convolutions of the film strip to walk or wander. By walking or wandering, it is meant that adjacent convolutions can shift relative to each other. Shifting might cause the undried deposited processing fluid to contact dry areas on the film, thereby adversely affecting the viewing of the film's images. This problem is accentuated should the film include a section for magnetic sound recording because the sound reproduction would be adversely affected.
Although avoidance of the draft on the flanges of a molded one-piece spool is possible with separable snap-together spools, there remain problems. Exemplary of the state of the art, with respect to such separable spools, are those described in the following U.S. Pat. Nos.: 2,575,025, issued to Mihalyi; 3,035,786, issued to Pieplow, et al.; 3,250,482, issued to Whitnah; 3,275,256, issued to Campbell, et al., 3,797,777, issued to Hosono, et al.; 3,869,099, issued to Inaga; and 4,015,790, issued to Gelardi, et al. For example, those two-piece spools relying upon a frictional interference fit between the complementary and cooperating components achieving the interlock, suffer from the shortcoming that tolerance variations of the interfitting components might create a loose fit allowing shifting of the spool pieces. Thus, the spool's flanges might widen relative to each other, thereby resulting in the noted undesirable walking of the film strip, as well as the mentioned drawbacks attendant with such walking.
Another problem arising from use of a molded one-piece spool occurs during manual loading of the spool with the unexposed film into the cassette. With the conventional manual loading procedure, use is made of a light-tight container for storing the unexposed film during transportation. During the loading, the spool is removed from the container and mounted on a suitable cassette spindle for subsequent threading of the film. Removal of the film spool is necessitated because the container is too large for insertion into the highly compact film cassette of the type noted. Since the film is removed, it follows that the entire loading and subsequent film threading operations be performed in darkness. Otherwise, unintended fogging of the inner convolutions of the film becomes a problem. Of course, the additional container as well as associated ambient darkness requirement increases substantially the time, labor and costs associated with loading.
It will be appreciated, therefore, that conventional film spools particularly of the type usable in the noted multipurpose film cassettes suffer from several potential shortcomings. Moreover, these potential problems are further compounded by the requirement that the cassette and its components including the photographic film spool must be capable of mass production and manufacturing techniques as well as be within tolerance levels incident to such techniques for the system to be acceptable in a competitive commercial market.